TITLE: The Gang-of-Four Book at Fifteen
AUTHOR: Eugene Wallingford
DATE: November 18, 2009  6:45 AM
DESC: 
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BODY:
One of the fun parts of teaching software engineering
this semester has been revisiting some basic patterns
in the design part of the course, and now as we discuss
refactoring in the part of the course that deals with
implementation and maintenance.  2009 is the 15th
anniversary of the publication of <EM>Design Patterns</EM>,
the book that launched software patterns into the
consciousness of mainstream developers.  Some folks
reminisced about the event at OOPSLA this year, but I
wasn't able to make it to Orlando.  OOPSLA 2004 had a
great 10th-anniversary celebration, which I had the
good fortune to attend
<A HREF="http://www.cs.uni.edu/~wallingf/blog/archives/monthly/2004-10.html#e2004-10-26T23_08_52.htm">
   and write about</A>.

I wasn't present at OOPSLA in 1994, when the book
created an unprecedented spectacle in the exhibit
hall; that just predates my own debut at OOPSLA.
But wish I had been!

InformIT recently ran a series of interviews with OO
and patterns luminaries, sharing their thoughts on
the book and on how patterns have changed the
landscape of software development.  The
<A HREF="http://www.informit.com/articles/article.aspx?p=1404182">
   interview with Brian Foote</A>
had a passage that I really liked:

<BLOCKQUOTE><EM>
<B>InformIT: How has </B>Design Patterns<B> changed your
impressions about the way software is built?</B>
<BR/><BR/>
The vision of reuse that we had in the object-oriented
community in hindsight seems like a God that Failed.  Just
as the Space Shuttle never lived up to its promised reuse
potential, libraries, frameworks, and components, while
effective in as far as they went, never became foundations
of routine software reuse that many had envisioned and
hoped.
<BR/><BR/>
Instead, designs themselves, design ideas, <B>patterns</B>
became the loci of reuse.  We craft our ideas, by hand,
into each new artifact we build.
</EM></BLOCKQUOTE>

This insight gets to the heart of why patterns matter.
Other forms of reuse have their place and use, but they
operate at a code level that is ultimately fragile in
the face of the different contexts in which our programs
operate.  So they are, by necessity, limited as vehicles
for reuse.

Design ideas are less specific, more malleable.  They
apply in a million contexts, though never in quite the
same way.  We mold them to the context of our program.
The patterns we see in our designs and tests and
implementations give us the abstract raw material out
of which to create our programs.  We still strive for
reuse, but at a different level of thinking and working.

Read the full interview linked above.  It is typical
Brian Foote: entertaining and full of ideas presented
slightly askew from the typical vantage point.  That
twist helps me to think differently about things that
may have otherwise become commonplace.  And as so often
happens, I had to
<A HREF="http://www.merriam-webster.com/dictionary/lahar">
   look a word up in the dictionary</A>
before I reached the end.  I always seem to learn
something from Brian!
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